JP7077965B2 - Compositions for optical materials - Google Patents

Description

The present invention relates to optical components such as plastic lenses, prisms, optical fibers, information recording substrates, filters, and adhesives, and particularly compositions for optical materials used in optical lenses such as plastic lenses for spectacles.

The main performances of optical materials, especially plastic materials required for spectacle lenses, are heat resistance, low specific gravity, high transparency and low yellowness, and high refractive index and high Abbe number. In order to achieve a refractive index and a high Abbe number, polymerizable compositions for optical materials containing a polyepisulfide compound have been proposed (Patent Documents 1 to 3).
Further, optical lenses such as spectacle lenses are dyed, hard-coated, and anti-reflection coated for the purpose of improving designability, durability, and optical characteristics. In the process of applying them, the optical material is exposed to high temperatures, which can cause problems due to thermal deformation. Therefore, it is desired to improve the heat resistance of the optical material. Various comonomers are added to the composition for an optical material for the purpose of increasing the refractive index of the optical material and improving the color tone stability.
However, the addition of comonomer tends to reduce the crosslink density of the optical material obtained after polymerization and deteriorate the heat resistance, and the amount of comonomer added is limited from the viewpoint of heat resistance, and the characteristics of the optical material can be improved. There is a problem that is limited. A composition for an optical material is desired, which can increase the allowable amount of comonomer addition by improving the standard heat resistance and can design an optical material having a wide range of physical characteristics.

Japanese Unexamined Patent Publication No. 10-298287 Japanese Unexamined Patent Publication No. 2001-002933 Japanese Unexamined Patent Publication No. 2010-242093

It is desired to provide a composition for an optical material capable of designing an optical material having an improved heat resistance and having a wide range of physical characteristics.

The present inventors have found that it is possible to design an optical material having a wide range of physical properties by a specific composition containing a compound represented by the following formula (1) and polythiol (a). That is, the present invention is as follows.

［２］ 化合物（Ａ）の含有量が、組成物総量に対して、２０～８０質量％である、［１］に記載の組成物。
［３］ さらに硫黄を含有する、［１］または［２］に記載の組成物。
［４］ さらに下記式（２）で表される化合物（Ｂ）を含有する、［１］～［３］のいずれかに記載の組成物。

（式中、ｍは０～４の整数を示し、ｎは０～２の整数を示す。）
［５］ 化合物（Ｂ）の含有量が、組成物総量に対して、０～７０質量％である、［４］に記載の組成物。
［６］ ポリチオール（ａ）は、１，２，６，７－テトラメルカプト－４－チアへプタン、メタンジチオール、（スルファニルメチルジスルファニル）メタンチオール、ビス（２－メルカプトエチル）スルフィド、２，５－ビス（メルカプトメチル）－１，４－ジチアン、１，２－ビス（２－メルカプトエチルチオ）－３－メルカプトプロパン、４，８－ジメルカプトメチル－１，１１－ジメルカプト－３，６，９－トリチアウンデカン、４，７－ジメルカプトメチル－１，１１－ジメルカプト－３，６，９－トリチアウンデカン、５，７－ジメルカプトメチル－１，１１－ジメルカプト－３，６，９－トリチアウンデカン、１，１，３，３－テトラキス（メルカプトメチルチオ）プロパン、テトラメルカプトペンタエリスリトール、１，３－ビス（メルカプトメチル）ベンゼン、１，４－ビス（メルカプトメチル）ベンゼン、及びチイランメタンチオールから選択される少なくとも１種である、［１］～［５］のいずれかに記載の組成物。
［７］ 組成物総量に対して、
化合物（Ａ） ２０～８０質量％；
化合物（Ｂ） ０～７０質量％；
ポリチオール（ａ） ０．１～２０質量％；及び
硫黄 ０～２５質量％；
を含有する［１］～［６］のいずれかに記載の組成物。
［７ａ］ 組成物総量に対して、
化合物（Ａ） ２０～８０質量％；
化合物（Ｂ） ０～７０質量％；
ポリチオール（ａ） ０．１～２０質量％；
硫黄 ０～２５質量％；
重合触媒 ０～１０質量％；及び
重合調整剤 ０～５質量％
を含有する［１］～［７］のいずれかに記載の組成物。
［８］ ［１］～［７］、［７ａ］のいずれかに記載の組成物を硬化した光学材料。
［９］ ［８］に記載の光学材料を含む光学レンズ。 [1] A composition for an optical material containing the compound (A) and the polythiol (a) represented by the following formula (1) and not containing 1,2,3,5,6-pentathiepan (b).

[2] The composition according to [1], wherein the content of the compound (A) is 20 to 80% by mass with respect to the total amount of the composition.
[3] The composition according to [1] or [2], which further contains sulfur.
[4] The composition according to any one of [1] to [3], further containing the compound (B) represented by the following formula (2).

(In the formula, m indicates an integer of 0 to 4, and n indicates an integer of 0 to 2.)
[5] The composition according to [4], wherein the content of the compound (B) is 0 to 70% by mass with respect to the total amount of the composition .
[6] Polythiol (a) is 1,2,6,7-tetramercapto-4-thiaheptane, methanedithiol, (sulfanylmethyldisulfanyl) methanethiol, bis (2-mercaptoethyl) sulfide, 2,5. -Bis (mercaptomethyl) -1,4-ditian, 1,2-bis (2-mercaptoethylthio) -3-mercaptopropane, 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9 -Trithiaundecane, 4,7-Dimercaptomethyl-1,11-Dimercapto-3,6,9-Trithiandecan, 5,7-Dimercaptomethyl-1,11-Dimercapto-3,6,9-Tri From thiaundecane, 1,1,3,3-tetrakis (mercaptomethylthio) propane, tetramercaptopentaerythritol, 1,3-bis (mercaptomethyl) benzene, 1,4-bis (mercaptomethyl) benzene, and thiranmethanethiol The composition according to any one of [1] to [5], which is at least one selected.
[7] With respect to the total amount of the composition
Compound (A) 20-80% by mass;
Compound (B) 0-70% by mass;
Polythiol (a) 0.1 to 20% by mass; and sulfur 0 to 25% by mass;
The composition according to any one of [1] to [6] containing.
[7a] With respect to the total amount of the composition
Compound (A) 20-80% by mass;
Compound (B) 0-70% by mass;
Polythiol (a) 0.1 to 20% by mass;
Sulfur 0-25% by mass;
Polymerization catalyst 0-10% by mass; and polymerization modifier 0-5% by mass
The composition according to any one of [1] to [7] containing.
[8] An optical material obtained by curing the composition according to any one of [1] to [7] and [7a].
[9] An optical lens containing the optical material according to [8].

The composition for an optical material of the present invention has one or more of the following effects.
(1) By using the composition for an optical material of the present invention, heat resistance is improved, the allowable amount of comonomer added is increased, and an optical material having a wide range of physical characteristics can be designed.
(2) An optical material having both excellent heat resistance and a high refractive index can be obtained.

Hereinafter, the present invention will be described in detail by showing embodiments and examples, but the present invention is not limited to the embodiments and examples shown below, and is arbitrary as long as it does not deviate from the gist of the present invention. Can be changed to.

本形態の光学材料用組成物は、必要に応じて、化合物（Ｂ）、硫黄、および重合触媒などの他の成分を含有する。
以下、各構成要素について詳細に説明する。One embodiment of the present invention is for an optical material containing the compound (A) and the polythiol (a) represented by the following formula (1) and not containing 1,2,3,5,6-pentathiepan (b). Regarding the composition.

The composition for optical materials of this embodiment contains other components such as compound (B), sulfur, and a polymerization catalyst, if necessary.
Hereinafter, each component will be described in detail.

この化合物の入手方法は特に限定されないが、例えば、テトラメルカプトペンタエリスリトールを原料として特開平０９－１１０９７９記載の方法にて合成可能であり好適に用いることができる。[Compound (A)]
The compound (A) is a thioether compound having four thioepoxy groups represented by the following formula (1), and has an effect of increasing the refractive index and heat resistance of the optical material.

The method for obtaining this compound is not particularly limited, but for example, it can be synthesized by the method described in JP-A-09-110979 using tetramercaptopentaerythritol as a raw material and can be preferably used.

The ratio of the compound (A) in the composition for optical materials is 0.1 to 99.5% by mass, preferably 3 to 90% by mass, and more preferably 5 to 90% by mass with respect to the total amount of the composition. It is more preferably 10 to 90% by mass, still more preferably 20 to 90% by mass, particularly preferably 20 to 80% by mass, and most preferably 30 to 80% by mass. Within this range, a sufficient effect of improving heat resistance can be obtained.

[Polythiol (a)]
Polythiol (a) is a thiol compound having two or more mercapto groups per molecule. Polythiol (a) has an effect of improving the color tone of the resin obtained from the composition for optical materials of the present invention during heating.
The polythiol used in the present invention is not particularly limited, but since it has a high color tone improving effect, preferred specific examples thereof include 1,2,6,7-tetramercapto-4-thiaheptane, methanedithiol, (sulfanylmethyldi). Sulfanyl) methanethiol, bis (2-mercaptoethyl) sulfide, 2,5-bis (mercaptomethyl) -1,4-ditian, 1,2-bis (2-mercaptoethylthio) -3-mercaptopropane, 4, 8-Dimercaptomethyl-1,11-Dimercapto-3,6,9-Trithiandecan, 4,7-Dimercaptomethyl-1,11-Dimercapto-3,6,9-Trithiandecan, 5,7- Dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 1,1,3,3-tetrakis (mercaptomethylthio) propane, tetramercaptopentaerythritol, 1,3-bis (mercaptomethyl) benzene , 1,4-bis (mercaptomethyl) benzene, and thilane methanethiol, with bis (2-mercaptoethyl) sulfide, 1,2,6,7-tetramercapto-4-thiaheptane being particularly preferred. As these, commercially available products or products synthesized by a known method can be used, and two or more types can be used in combination. As these, commercially available products or products synthesized by a known method can be used, and two or more types can be used in combination.

In the composition for optical materials, the proportion of polythiol (a) is preferably 0.1 to 25% by mass, more preferably 0.1 to 20% by mass, still more preferably 0.5, based on the total amount of the composition. It is about 20% by mass, particularly preferably 0.5 to 15% by mass, and most preferably 0.5 to 10% by mass. Within this range, the balance between the color tone stabilizing effect and the heat resistance is improved.

なお、「１，２，３，５，６－ペンタチエパン（ｂ）を含有しない」とは、１，２，３，５，６－ペンタチエパン（ｂ）を光学材料用組成物に意図的に添加しないことを意味し、以下の態様を含む：
１）本発明の光学材料用組成物中に１，２，３，５，６－ペンタチエパン（ｂ）が全く存在しない；及び
２）本発明の光学材料用組成物中に１，２，３，５，６－ペンタチエパン（ｂ）が実質的に存在しない。
「１，２，３，５，６－ペンタチエパン（ｂ）が実質的に存在しない」とは、典型的には、高速液体クロマトグラフィー（ＨＰＬＣ）による分析において、１，２，３，５，６－ペンタチエパン（ｂ）の含有量が、組成物総量に対して１ｐｐｍ未満であることをいい、好ましくは、１，２，３，５，６－ペンタチエパン（ｂ）の存在が検出されない（検出限界以下である）ことをいう。ＨＰＬＣによる分析は、例えば下記方法により行うことができる。
［ＨＰＬＣ分析方法］
カラムオーブン温度：４０℃
カラム：一般財団法人化学物質評価研究機構製 ＶＰ－ＯＤＳ、カラムサイズ４．６φ×１５０ｍｍ）
溶離液：アセトニトリル／蒸留水（容積比）＝５０／５０
溶液調製：サンプル５ｍｇを０．１％ギ酸溶液（アセトニトリル溶媒）１０ｍｌで希釈し分析試料とする。[1,2,3,5,6-pentathiepan (b)]
The composition for optical materials of the present invention does not contain 1,2,3,5,6-pentathiepan (b). 1,2,3,5,6-pentathiepan (b) is a compound represented by the following formula (b).

In addition, "does not contain 1,2,3,5,6-pentathiepan (b)" means that 1,2,3,5,6-pentathiepan (b) is not intentionally added to the composition for optical materials. Means that, including the following aspects:
1) No 1,2,3,5,6-pentathiepan (b) is present in the composition for optical materials of the present invention; and 2) 1,2,3 in the composition for optical materials of the present invention. 5,6-Pentatiepane (b) is virtually absent.
"The absence of 1,2,3,5,6-pentathiepan (b)" is typically 1,2,3,5,6 in high performance liquid chromatography (HPLC) analysis. -It means that the content of pentatiepan (b) is less than 1 ppm with respect to the total amount of the composition, preferably 1,2,3,5,6-the presence of pentatiepan (b) is not detected (below the detection limit). Is). The analysis by HPLC can be performed by, for example, the following method.
[HPLC analysis method]
Column oven temperature: 40 ° C
Column: VP-ODS manufactured by Chemicals Evaluation and Research Institute, column size 4.6φ x 150mm)
Eluent: acetonitrile / distilled water (volume ratio) = 50/50
Solution preparation: Dilute 5 mg of the sample with 10 ml of 0.1% formic acid solution (acetonitrile solvent) to prepare an analytical sample.

A cured product having improved heat resistance can be obtained by using a structure that does not contain 1,2,3,5,6-pentathiepan (b) but contains the compound (A) and the polythiol (a).

（式中、ｍは０～４の整数を示し、ｎは０～２の整数を示す。）[Compound (B)]
The composition for an optical material may contain compound (B), if necessary. Compound (B) is an episulfide compound having two episulfide groups represented by the following formula (2). The compound (B) can be copolymerized with the compound (A), and when used together with the compound (A), it has an effect of enhancing the curing reactivity.

(In the formula, m indicates an integer of 0 to 4, and n indicates an integer of 0 to 2.)

Of these, bis (β-epithiopropyl) sulfide and bis (β-epithiopropyl) disulfide are preferable, and bis (β-epithiopropyl) sulfide is particularly preferable. The bis (β-epithiopropyl) sulfide corresponds to the compound of m = n = 0 in the above formula (2), and the bis (β-epithiopropyl) disulfide corresponds to m = 0 and n = 1 in the above formula (2). Corresponds to the compound that is.

The content of the compound (B) in the composition for an optical material is 0 to 70% by mass, preferably 0 to 60% by mass, and more preferably 0 to 50% by mass with respect to the total amount of the composition. Within this range, the curing reactivity can be improved while ensuring heat resistance.

The mass ratio of compound (A) to compound (B) (compound (A): compound (B)) is preferably 20:80 to 100: 0, and preferably 30:70 to 100: 0. More preferably, it is more preferably 40:60 to 100: 0. Within this range, heat resistance can be improved while maintaining a high refractive index.

[sulfur]
The composition for optical materials may contain sulfur, if necessary. Sulfur has the effect of improving the refractive index of the optical material (resin) obtained from the composition for optical materials of the present invention.
The shape of sulfur used in the present invention may be any shape. Specifically, examples of sulfur include fine powder sulfur, colloidal sulfur, precipitated sulfur, crystalline sulfur, sublimation sulfur, and the like, and from the viewpoint of dissolution rate, fine powder sulfur is preferable.
The particle size (diameter) of sulfur used in the present invention is preferably smaller than 10 mesh. When the particle size of sulfur is larger than 10 mesh, it is difficult for sulfur to dissolve completely. The particle size of sulfur is more preferably smaller than 30 mesh and most preferably smaller than 60 mesh.
The purity of sulfur used in the present invention is preferably 98% or more, more preferably 99.0% or more, still more preferably 99.5% or more, and most preferably 99.9% or more. When the purity of sulfur is 98% or more, the color tone of the obtained optical material is further improved as compared with the case where it is less than 98%.
Sulfur satisfying the above conditions is easily available on the market and can be preferably used.

The proportion of sulfur in the composition for optical materials is 0 to 40% by mass (for example, 1 to 40% by mass), preferably 0 to 30% by mass (for example, 5 to 30% by mass, 10) with respect to the total amount of the composition. ~ 30% by mass), more preferably 0 to 25% by mass (for example, 5 to 25% by mass), and particularly preferably 0 to 20% by mass (for example, 5 to 20% by mass). This is because the range is excellent in the balance between the effect of improving the refractive index and the solubility.

An example of the composition of a preferred composition for an optical material is as follows.
For the total amount of composition
Compound (A) 20 to 80% by mass (more preferably 30 to 80% by mass);
Compound (B) 0 to 70% by mass (more preferably 0 to 60% by mass);
Polythiol (a) 0.1 to 20% by weight (more preferably 0.5 to 10% by weight); and sulfur 0 to 25% by weight (more preferably 0 to 20% by weight);
Contains,
It does not contain 1,2,3,5,6-pentathiepan (b) (eg, less than 1 ppm in analysis by HPLC).
Compositions for optical materials.
Another example of the composition of a preferred optical material composition is as follows.
For the total amount of composition
Compound (A) 20 to 80% by mass (more preferably 30 to 80% by mass);
Compound (B) 0 to 70% by mass (more preferably 0 to 60% by mass);
Polythiol (a) 0.1 to 20% by mass (more preferably 0.5 to 10% by mass);
Sulfur 0-25% by weight (more preferably 0-20% by weight);
Polymerization catalyst 0-10% by weight (more preferably 0-5% by weight); and polymerization modifier 0-5% by weight (more preferably 0.0001-5.0% by weight)
Contains,
It does not contain 1,2,3,5,6-pentathiepan (b) (eg, less than 1 ppm in analysis by HPLC).
Compositions for optical materials.

[Other ingredients]
Further, the composition for an optical material of the present invention may contain another polymerizable compound that can be copolymerized with the compound (A).
Examples of other polymerizable compounds include episulfide compounds other than the compound (A) and the compound (B), vinyl compounds, methacrylic compounds, acrylic compounds, and allyl compounds.
The amount of the other polymerizable compound added is not particularly limited as long as it does not impair the effects of the present invention, and is, for example, 0 to 30% by mass with respect to the total amount of the composition.

Further, for the purpose of improving various performances such as oxidation resistance, weather resistance, dyeability, strength and refractive index, as various performance improving agents, the composition component of the present invention (polymer obtained by prepolymerizing the composition component) is used. It is also possible to polymerize and cure by adding a compound that can react with part or all of (including).
Specific examples of compounds that can react with some or all of such compositional components include epoxy compounds, iso (thio) cyanates, carboxylic acids, carboxylic acid anhydrides, phenols, amines, and vinyl compounds. , Allyl compounds, acrylic compounds, and methacryl compounds. The amount of these compounds added is not particularly limited as long as it does not impair the effects of the present invention, and is, for example, 0 to 10% by mass with respect to the total amount of the composition.

Further, the composition for an optical material may contain a known polymerization catalyst and / or polymerization modifier for polymerization curing. One form of the composition for an optical material further comprises a polymerization catalyst.
One form of the composition for an optical material further comprises a polymerization catalyst.
Examples of the polymerization catalyst include amines, phosphins, quaternary ammonium salts, quaternary phosphonium salts, tertiary sulfonium salts, secondary iodonium salts, mineral acids, Lewis acids, organic acids, silicic acids, and quaternary compounds. Borate fluorides, peroxides, azized compounds, condensates of aldehydes and ammonia compounds, guanidines, thioureas, thiazoles, sulfenamides, thiurams, dithiocarbamates, xanthogenates, Acidic phosphate esters and the like can be mentioned. Preferred are amines, phosphines, quaternary ammonium salts, and quaternary phosphonium salts. The polymerization catalyst may be used alone or in combination of two or more.
The amount of the polymerization catalyst added is not particularly limited, and is, for example, 0.0001 to 10% by mass with respect to the total amount of the composition.
One form of the composition for an optical material further comprises a polymerization modifier.
Examples of the polymerization modifier include halides of Groups 13 to 16 in the long-term periodic table. Of these, preferred are halides of silicon, germanium, tin and antimony, and more preferred are chlorides of germanium, tin and antimony having an alkyl group. The polymerization modifier may be used alone or in combination of two or more.
The amount of the polymerization modifier added is not particularly limited, and is, for example, 0.0001 to 5.0% by mass with respect to the total amount of the composition.

Further, known additives such as antioxidants, brewing agents, ultraviolet absorbers, deodorants, adhesion improving agents and mold release improving agents can also be added. The amount of these additives is not particularly limited as long as it does not impair the effects of the present invention, and is, for example, 0 to 10% by mass with respect to the total amount of the composition.

[Composition for optical materials]
The composition for an optical material of the present invention is prepared by mixing compound (A), polythiol (a), and, if necessary, compound (B), sulfur, and other components in a uniform state. ..

[Curing of composition for optical materials]
The composition for an optical material can be obtained as an optical material by casting it into a mold such as a mold and polymerizing it. It is preferable to perform a degassing treatment in advance before injecting the polymerizable composition for an optical material into a mold from the viewpoint of achieving a high degree of transparency of the optical material.
When casting the composition for an optical material of the present invention, it is preferable to filter and remove impurities with a filter or the like having a pore size of about 0.1 to 5 μm from the viewpoint of improving the quality of the optical material of the present invention.

Polymerization (curing) of the composition for optical materials of the present invention is usually carried out under the following conditions.
The curing time is usually 1 to 100 hours, and the curing temperature is usually −10 ° C. to 140 ° C. Polymerization (curing) is carried out by a step of holding at a predetermined polymerization temperature for a predetermined time, a step of raising the temperature from 0.1 ° C. to 100 ° C./h, a step of lowering the temperature from 0.1 ° C. to 100 ° C./h, or these. The steps of are combined. The curing time refers to the polymerization curing time including the temperature raising process and the temperature lowering process, and in addition to the step of holding at a predetermined polymerization (curing) temperature, the temperature is raised and cooled to a predetermined polymerization (curing) temperature. Including the process of
Further, it is preferable to perform an annealing treatment on the obtained optical material at a temperature of 50 to 150 ° C. for about 10 minutes to 5 hours after the curing is completed in order to remove the distortion of the optical material of the present invention. Further, the obtained optical material may be subjected to surface treatment such as dyeing, hard coating, impact resistance coating, antireflection, and antifogging property, if necessary.

As described above, an optical material can be produced by polymerizing and curing the composition for an optical material. The present invention also includes a method for producing an optical material, which comprises polymerizing and curing the composition for an optical material.
Further, an optical material (molded body; cured product; cured resin) obtained by curing the composition for an optical material is also included in the present invention.

The composition for an optical material of the present invention contains the compound (A) and the polythiol (a), and does not contain 1,2,3,5,6-pentathiepan (b), thereby providing excellent heat resistance. This can be achieved, and the influence of the decrease in heat resistance due to the addition of other comonomer can be reduced. Therefore, it is possible to blend various comonomer into the composition for optical material and increase the blending amount thereof, which makes it possible to design an optical material having a wide range of physical characteristics.
In particular, the composition for an optical material according to an embodiment of the present invention can provide an optical material having particularly excellent heat resistance while maintaining a high refractive index.

The refractive index of the optical material when the composition for an optical material is cured is preferably 1.70 or more, more preferably 1.72 or more, and particularly preferably 1.73 or more. The refractive index can be measured by a refractive index meter, and is a value measured at 25 ° C. and an e-line (wavelength 546.1 nm).
As for the heat resistance of the optical material, it is preferable that there is no softening point when the temperature of the optical material is raised, or the softening point is preferably 50 ° C. or higher, more preferably 60 ° C. or higher, and particularly preferably 65 ° C. or higher. .. The softening point can be measured by TMA (thermomechanical analysis). The smaller the peak value of DTMA, which is the temperature differential curve of the TMA curve, the less likely it is to soften due to heat. Therefore, the peak value of DTMA is preferably 1.5 μm / ° C or less, and preferably 1 μm / ° C or less. More preferred.

The optical material of the present invention is useful for various applications such as optical members, mechanical parts materials, electrical / electronic parts materials, automobile parts materials, civil engineering and building materials, molding materials, as well as paints and adhesive materials. .. Among them, optical materials such as spectacle lenses, image pickup lenses for (digital) cameras, light beam condensing lenses, lenses for light diffusion, encapsulants for LEDs, optical adhesives, bonding materials for optical transmission, optical fibers. , Prism, filter, diffraction grid, watch glass, transparent glass such as cover glass for display devices, optical applications such as cover glass; substrate for display elements such as LCD, organic EL and PDP, substrate for color filter, substrate for touch panel , Information recording substrate, display backlight, light guide plate, display protective film, antireflection film, antifogging film and other coating agents (coating film) and the like are suitable for display devices. As the optical material, an optical material such as an optical lens, a prism, an optical fiber, an information recording substrate, and a filter, particularly an optical lens is preferable.
Since the optical lens manufactured by using the composition for optical materials of the present invention is excellent in stability, hue, transparency and the like, conventionally expensive high refractive index glass lenses such as telescopes, binoculars and television projectors have been used. It can be used in the field where it was, and it is extremely useful. If necessary, it is preferably used in the form of an aspherical lens.

Hereinafter, the present invention will be specifically described with reference to Examples, but the embodiments can be appropriately changed as long as the effects of the present invention are exhibited.

The analysis and evaluation of the optical material was performed by the following method.
[Refractive index of optical material]
The refractive index of the optical material was measured by using a digital precision refractive index meter (KPR-2000, manufactured by Shimadzu Corporation) at 25 ° C.
[Evaluation of heat resistance of optical materials]
A sample was cut into a thickness of 3 mm, a load of 50 g was applied to a pin of 0.5 mmφ, the temperature was raised at 10 ° C./min, and TMA measurement (TMA / SS6100 manufactured by Seiko Instruments) was performed. The evaluation was performed based on the peak temperature of DTMA, which is a temperature differential curve, and the peak value of DTMA.
It is evaluated that the smaller the DTMA peak value, the less likely it is to soften due to heat and the higher the heat resistance. In particular, when the peak value was negative or there was no peak, no softening point was set. A DTMDTMA peak value of 1.0 or less was evaluated as A, an DTMDTMA peak value of more than 1.0 and 1.5 or less was evaluated as B, and a DTMA peak value of more than 1.5 was evaluated as C.

[Synthesis Example 1]
To 10.0 g (0.050 mol) of tetramercaptopentaerythritol, 50 mL of methanol was added, and the mixture was cooled to 5 ° C. After adding 0.42 g (0.0049 mol) of a 48% aqueous sodium hydroxide solution to the solution, 20.3 g (0.22 mol) of epichlorohydrin was added dropwise while keeping the solution at 15 ° C. or lower. After completion of the dropping, the mixture was further stirred at 5 ° C. for 1 hour.
Then, while cooling the solution to 5 ° C., a solution prepared by dissolving 16.3 g (0.20 mol) of a 48% sodium hydroxide aqueous solution in 20 mL of methanol was added dropwise. After the completion of the dropping, the mixture was further stirred for 2 hours, and 100 mL of toluene and 100 mL of water were added. The toluene layer was washed with water three times, and the solvent was distilled off to obtain 20.1 g (0.047 mol) of tetrakis (β-epoxypropylthiomethyl) methane.
To 20.1 g (0.047 mol) of the obtained tetrakis (β-epoxypropylthiomethyl) methane, 100 mL of toluene, 100 mL of methanol, 1.24 g (0.012 mol) of acetic anhydride, and 30.5 g (0.40 mol) of thiourea. Was added, and the mixture was stirred at 20 ° C. for 24 hours. Then, 400 mL of toluene and 400 mL of 5% sulfuric acid were added, and the toluene layer was washed with water three times, and the solvent was distilled off to obtain 16.8 g of a crude product of tetrakis (β-epithiopropylthiomethyl) methane. The crude product was further purified by a silica gel column to obtain 11.2 g (0.023 mol) of tetrakis (β-epithiopropylthiomethyl) methane (hereinafter referred to as compound A1).
Compound A1 used in the following experiments was synthesized by this method.

[Example 1]
80 parts by mass of tetrakis (β-epithiopropylthiomethyl) methane (compound A1) as compound (A), 20 parts by mass of bis (2-mercaptoethyl) sulfide (compound a1) as compound, and tetra as a polymerization catalyst. Vacuum degassing was performed while mixing 0.02 part by mass of -n-butylphosphonium bromide and 0.05 part by mass of di-n-butyltin dichloride as a polymerization modifier to obtain a composition for an optical material.
The obtained composition for optical materials was heated at 30 ° C. for 10 hours, heated to 100 ° C. over 10 hours, and finally heated at 100 ° C. for 5 hours to polymerize and cure. After allowing to cool, annealing treatment was performed at 120 ° C. for 30 minutes. The evaluations of the obtained optical materials are summarized in Table 1.

[Examples 2 to 11, Comparative Examples 1 to 4]
An optical material was obtained by performing the same operation as in Example 1 according to the composition shown in Table 1.
The evaluations of the obtained optical materials are summarized in Table 1.

The numerical values in the table indicate the content (parts by mass) of the compound in the composition. In addition, the notations a1 to a3 and B1 and B2 shown together with the numerical values in the table indicate the compounds used. The following compounds were used as the compounds in the table.
A1: Tetrakiss (β-epithiopropylthiomethyl) Methane a1: Bis (2-mercaptoethyl) Sulfide a2: 1,3-bis (mercaptomethyl) Benzene a3: 1,2,6,7-Tetramercapto-4- Thiaheptane B1: Bis (β-Epithiopropyl) Sulfide B2: Bis (β-Epithiopropyl) Disulfide

The compound a3 can be synthesized, for example, by the method described in JP-A-2005-263791.

From Table 1 above, 1,2,3,5,6-pentathiepan containing the compound (A) and the polythiol (a) represented by the formula (1), and optionally the compound (B) and / or sulfur. When the composition for an optical material not containing (b) is used (Examples 1 to 11), it is confirmed that an optical material having excellent heat resistance while maintaining a high refractive index can be obtained.
On the other hand, in Comparative Example 1,3,4 not containing the compound (A) and Comparative Example 2 containing 1,2,3,5,6-pentathiepan (b), it is confirmed that the heat resistance is inferior.

The cured product obtained by polymerizing and curing the composition for optical materials of the present invention can be suitably used as an optical material such as a plastic lens, a prism, an optical fiber, an information recording substrate, a filter, and an adhesive.

Claims (6)

For the total amount of composition
Compound (A) represented by the following formula (1) 30 to 80% by mass;
Compound (B) represented by the following formula (2) 0 to 70% by mass;
Polythiol (a) 0.1-20% by weight; and
Sulfur 0-25% by mass;
A composition for an optical material containing 1,2,3,5,6-pentathiepan (b).

(In the formula, m indicates an integer of 0 to 4, and n indicates an integer of 0 to 2.) The composition according to claim 1 , which contains sulfur . The composition according to claim 1 or 2 , which comprises compound (B). Polythiol (a) is 1,2,6,7-tetramercapto-4-thiaheptane, methanedithiol, (sulfanylmethyldisulfanyl) methanethiol, bis (2-mercaptoethyl) sulfide, 2,5-bis ( Mercaptomethyl) -1,4-ditian, 1,2-bis (2-mercaptoethylthio) -3-mercaptopropane, 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithia Undecane, 4,7-Dimercaptomethyl-1,11-Dimercapto-3,6,9-Trithian Undecane, 5,7-Dimercaptomethyl-1,11-Dimercapto-3,6,9-Trithian Undecane, Selected from 1,1,3,3-tetrakis (mercaptomethylthio) propane, tetramercaptopentaerythritol, 1,3-bis (mercaptomethyl) benzene, 1,4-bis (mercaptomethyl) benzene, and thiranmethanethiol. The composition according to any one of claims 1 to 3, which is at least one kind. An optical material obtained by curing the composition according to any one of claims 1 to 4 . An optical lens comprising the optical material according to claim 5 .